fix: root ExposedName must be 'Root' from JSON structure, not empty

Compared BSON before/after Studio Pro fix and found:
- Root ExposedName must match JSON structure root (typically 'Root'),
  not empty string. Empty ExposedName causes CE5015 "Custom name does
  not match schema element '(Object)'"
- Export value JsonPath uses original JSON key (not ExposedName)
- Export object elements need CustomHandlerCall: null and ElementType
  from Kind field (Array for array containers)
- Export Kind field set to "Array" for array elements

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ako

mdl/executor/cmd_export_mappings.go

@@ -301,27 +301,26 @@ func buildExportMappingElementModel(moduleName string, def *ast.ExportMappingEle
 		var jsonPath string
 		if isRoot {
 			jsonPath = parentPath // "(Object)"
-			elem.ExposedName = ""
+			elem.ExposedName = "Root" // default; overridden from JSON structure below
 			if info, ok := jsElements[jsonPath]; ok {
+				elem.ExposedName = info.ExposedName
 				elem.MaxOccurs = info.MaxOccurs
 			}
 			elem.JsonPath = jsonPath
 		} else {
 			// Look up by original JSON key, then use ExposedName for the mapping's JsonPath
 			lookupPath := parentPath + "|" + def.JsonName
+			jsonPath = lookupPath // export JsonPath always uses original JSON key
 			if info, ok := jsElements[lookupPath]; ok {
 				elem.ExposedName = info.ExposedName
 				elem.MaxOccurs = info.MaxOccurs
-				jsonPath = parentPath + "|" + info.ExposedName
 				if info.ElementType == "Array" {
-					jsonPath = lookupPath // array keeps original path
+					elem.Kind = "Array"
 				}
-			} else {
-				jsonPath = lookupPath
 			}
 			elem.JsonPath = jsonPath
-			// Array children use the item path
-			if jsElements[lookupPath] != nil && jsElements[lookupPath].ElementType == "Array" {
+			// Array children use the item path for recursion
+			if elem.Kind == "Array" {
 				jsonPath = lookupPath + "|(Object)"
 			}
 		}

mdl/executor/cmd_import_mappings.go

@@ -281,7 +281,10 @@ func buildImportMappingElementModel(moduleName string, def *ast.ImportMappingEle
 		var jsonPath string
 		if isRoot {
 			jsonPath = "(Object)"
-			elem.ExposedName = ""
+			elem.ExposedName = "Root" // default; overridden from JSON structure below
+			if info, ok := jsElements["(Object)"]; ok {
+				elem.ExposedName = info.ExposedName
+			}
 			elem.JsonPath = jsonPath
 		} else {
 			// Look up by original JSON key, then use ExposedName for the mapping's JsonPath

sdk/mpr/writer_export_mapping.go

@@ -141,8 +141,9 @@ func serializeExportObjectElement(id string, elem *model.ExportMappingElement, p
 		"MaxOccurs":                         maxOccurs,
 		"Nillable":                          true,
 		"IsDefaultType":                     false,
-		"ElementType":                       "Object",
+		"ElementType":                       elementTypeForKind(elem.Kind),
 		"Documentation":                     "",
+		"CustomHandlerCall":                 nil,
 	}
 }